EXHIBIT 99.20

                                 PROMISSORY NOTE


Amount:    $1,666,667.25                                  Minneapolis, Minnesota

Due Date:  January 15, 2010                                    December 20, 2002

Re:  National Mercantile Bancorp


FOR VALUE RECEIVED, the undersigned ("Maker") promises to pay to the order of
CARL R. POHLAD, TRUSTEE OF THE REVOCABLE TRUST NO. 2 OF CARL R. POHLAD CREATED
U/A DATED 5/23/93, AS AMENDED, on January 15, 2010, the maturity date, the sum
of ONE MILLION SIX HUNDRED SIXTY-SIX THOUSAND SIX HUNDRED SIXTY-SEVEN AND 25/100
DOLLARS ($1,666,667.25) with interest from the date hereof at the RATE OF 3.31%
per annum, compounded annually, until paid. Interest accrued hereunder is
payable January 15, 2003, and annually thereafter. Interest is calculated on the
basis of actual days elapsed in a 365-day year. This Note is payable at 60 South
Sixth Street, Suite 3900, Minneapolis, Minnesota, 55402, or at such other place
as the holder may designate from time to time.

In the event of any default in the payment of principal or interest when due
hereunder, the entire principal balance and all accrued interest shall, at the
option of the holder of this Note, become immediately due and payable without
notice. Upon any default, the undersigned, and all endorsers, sureties and
guarantors hereof hereby jointly and severally agree to pay all costs and
expenses (including reasonable attorneys' fees) incurred in the collection of
this Note and waive presentment for payment, notice of nonpayment, protest,
notice of protest and diligence in enforcing payment hereunder or bringing suit
against any parties hereto. Each of the endorsers, sureties and guarantors
hereof consent that the time for payment may be extended, or this Note renewed
or other persons liable on this Note released, from time to time without notice
to them and without affecting their liability hereon.

This note may be prepaid in full or part at any time without penalty, provided
that all such prepayments are applied to accrued interest with the balance to
the principal balance hereof.

The undersigned, if more than one, shall be jointly and severally liable
hereunder, and the term "undersigned" wherever used herein, shall mean the
undersigned or any one or more of them.

This Note shall be governed by, interpreted and construed in accordance with the
laws of the State of Minnesota.

                                               MAKER:


                                               /s/ William M. Pohlad
                                               ---------------------------------
                                               William M. Pohlad

                                               60 South Sixth Street
                                               Suite 3900
                                               Minneapolis, Minnesota 55402